This invention relates generally to processes for decontaminating contaminated materials, such as chemical weapon components, and, more specifically, to processes for decontaminating contaminated materials without using incineration methods.
The decontaminating of contaminated material can be very difficult. This is especially the case with respect to the decommissioning of chemical weapons carrying chemical warfare agents. The principal problem in this regard is how to safely remove, neutralize and dispose of the extremely toxic chemical warfare agents used in such chemical weapons. Modern technology has become increasingly successful in the neutralization of these chemical warfare agentsxe2x80x94once the agents have been removed from the chemical weapon housing. However, after the bulk of the chemical warfare agents have been removed from the chemical weapons housings, the housings and their various components typically remain contaminated with residual amounts of the chemical warfare agents. The decontamination of these chemical weapon components remains a difficult problem.
Most prior art methods for decontaminating chemical weapon components have employed a two-step process. In a first step, the components are subjected to liquid chemicals or to high temperatures to remove and decompose essentially all of the chemical warfare agents adhering to the chemical weapon components. In a second step, residual vapors from the first step are incinerated to eliminate any and all residual chemical warfare agents in those vapors.
The incineration step has now been questioned, however, as possibly allowing potentially toxic combustion products to be released to the atmosphere. Accordingly, the incineration step has been banned in many industrial countries, including in the United States.
Thus, there is a need for a new method of decontaminating chemical weapon components which completely eliminates all traces of chemical warfare agents in an efficient and inexpensive manner, and without the use of an incineration step.
The invention satisfies this need. The invention is a process for the low temperature, non-incineration decontamination of contaminated materials containing hazardous agents, the process comprising (a) contacting the contaminated materials and the hazardous agents with steam at substantially ambient pressure in a substantially dry first heated vessel for a period of at least about 15 minutes, the steam being at a temperature of at least about 560xc2x0 C., whereby essentially all of the hazardous agents are removed from the contaminated materials, (b) removing a first gaseous discharge stream containing hazardous agents from the first heated vessel, the first gaseous discharge stream comprising a condensible moiety and a non-condensible moiety, (c) heating the first gaseous discharge stream at substantially ambient pressure in a substantially dry second vessel to at least about 500xc2x0 C. and maintaining the first gaseous discharge stream in the second vessel of at least about 500xc2x0 C. for a period of at least about one second in an atmosphere containing steam in a concentration greater than about 150% of stoichiometry, whereby at least about 99 weight percent of the hazardous agents within the first gaseous discharge stream are converted to non-hazardous agents, (d) removing a second gaseous discharge stream containing a reduced concentration of hazardous agents from the second vessel, the second gaseous discharge stream comprising a condensible moiety and a non-condensible moiety, (e) having a concentration of hazardous agents less than about 100 mg/l, (f) increasing the pH of the condensate to at least about 8.0 so as to reduce the concentration of hazardous agents within the condensate to less than about 1.0 mg/l, and (g) catalytically treating the non-condensible moiety of the second gaseous discharge stream in the presence of oxygen so that the concentration of hazardous agents within the non-condensible moiety of the second gaseous discharge stream is reduced to less than about 1.0 mg/m3 at standard temperature and pressure.
The process is especially applicable where the contaminated materials are chemical weapon components and the hazardous agents are chemical warfare agents.